The Advantage of Standing Up to Fight and the Evolution of Habitual Bipedalism in Hominins
Author Information
Author(s): David R. Carrier
Primary Institution: Department of Biology, University of Utah
Hypothesis
Does bipedal posture provide a performance advantage when striking with the forelimbs?
Conclusion
Bipedal posture provides a performance advantage for striking with the forelimbs, suggesting that sexual selection contributed to the evolution of habitual bipedalism in hominins.
Supporting Evidence
- Subjects did 43.70% more work when striking downward from a bipedal posture compared to a quadrupedal posture.
- Striking upward from a bipedal stance produced 47.49% more work than from a quadrupedal stance.
- Bipedal strikes resulted in 30.12% greater force impulses for side strikes and 43.04% greater for forward strikes compared to quadrupedal strikes.
Takeaway
Standing on two legs helps animals hit harder when they fight, which might be why humans and other great apes evolved to walk this way.
Methodology
The study measured striking performance of human subjects in both bipedal and quadrupedal postures using custom-designed instruments to quantify force and energy during strikes.
Potential Biases
Potential bias due to the experience level of subjects in martial arts or boxing.
Limitations
The study primarily used human subjects, which may not fully represent the biomechanics of habitual quadrupeds.
Participant Demographics
15 male subjects, average age 34.5 years, body mass 78.8 kg.
Statistical Information
P-Value
0.0018 for downward strikes, 0.014 for upward strikes
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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